Power Management

LT1761

Linear Technology

Low Dropout Negative Micropower Regulator in ThinSOT

Manufacturer: Linear Technology

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100mA, Low Noise, LDO Micropower Regulators in SOT-23 n Tiny 5-Lead SOT-23 Package n Low Noise: 20mVRMS (10Hz to 100kHz) n Low Quiescent Current: 20mA n Wide Input Voltage Range: 1.8V to 20V n Output Current: 100mA n Very Low Shutdown Current: < 0.1mA n Low Dropout Voltage: 300mV at 100mA n Fixed Output Voltages: 1.5V, 1.8V, 2V, 2.5V, 2.8V, 3V, 3.3V, 5V n Adjustable Output from 1.22V to 20V n Stable with 1mF Output Capacitor n Stable with Aluminum, Tantalum or Ceramic Capacitors n Reverse Battery Protected n No Reverse Current n No Protection Diodes Needed n Overcurrent and Overtemperature Protected The LT 1761 series are micropower, low noise, low dropout regulators. With an external 0.01 mF bypass capacitor, output noise drops to 20mVRMS over a 10Hz to 100kHz bandwidth. Designed for use in battery-powered systems, the low 20mA quiescent current makes them an ideal choice. In shutdown, quiescent current drops to less than 0.1mA. The devices are capable of operating over an input voltage from 1.8V to 20V, and can supply 100mA of output current with a dropout voltage of 300mV. Quies- cent current is well controlled, not rising in dropout as it does with many other regulators. The LT1761 regulators are stable with output capacitors as low as 1 mF. Small ceramic capacitors can be used without the series resistance required by other regulators. Internal protection circuitry includes reverse battery pro- tection, current limiting, thermal limiting and reverse current protection. The device is available in fixed output and as an adjustable device with a 1.22V reference voltage. The LT1761 regulators are available in the 5-lead SOT-23 package. 10Hz to 100kHz Output Noise 5V Low Noise Regulator n Cellular Phones n Pagers n Battery-Powered Systems n Frequency Synthesizers n Wireless Modems , LTC and LT are registered trademarks of Linear Technology Corporation. IN SHDN 0.01µF 10µF

1761 TA01

5.4V TO 20V BYP GND LT1761-5 5V AT100mA 20µVRMS NOISE 1µF VOUT 100µV/DIV 20µVRMS

1761 G48

(Note 1) LT1761ES5-BYP ORDER PART NUMBER TJMAX = 150°C, qJA = 250°C/ W SEE THE APPLICATIONS INFORMATION SECTION.

5 OUT

4 ADJ

4 BYP

Operating Junction Temperature Range S5 PART MARKING TJMAX = 150°C, qJA = 250°C/ W SEE THE APPLICATIONS INFORMATION SECTION. LT1761ES5-SD ORDER PART NUMBER S5 PART MARKING LTGC LTGH LT1761ES5-1.5 LT1761ES5-1.8 LT1761ES5-2 LT1761ES5-2.5 LT1761ES5-2.8 LT1761ES5-3 LT1761ES5-3.3 LT1761ES5-5 ORDER PART NUMBER S5 PART MARKING LTMT LTJM LTJE LTGD LTLB LTGE LTGF LTGG TJMAX = 150°C, qJA = 250°C/ W SEE THE APPLICATIONS INFORMATION SECTION. PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Input Voltage (Notes 3, 11) I LOAD = 100mA l 1.8 2.3 V Regulated Output Voltage LT1761-1.5 V IN = 2V, ILOAD = 1mA 1.478 1.5 1.522 V (Note 4) 2.5V < V IN < 20V, 1mA < ILOAD < 50mA l 1.457 1.5 1.538 V 2.5V < VIN < 20V, 1mA < ILOAD < 100mA l 1.436 1.5 1.555 V 2.8V < VIN < 20V, 1mA < ILOAD < 50mA l 1.750 1.8 1.845 V 2.8V < VIN < 20V, 1mA < ILOAD < 100mA l 1.725 1.8 1.860 V LT1761-2 V IN = 2.5V, ILOAD = 1mA 1.970 2 2.030 V 3V < VIN < 20V, 1mA < ILOAD < 50mA l 1.945 2 2.045 V 3V < VIN < 20V, 1mA < ILOAD < 100mA l 1.920 2 2.060 V LT1761-2.5 V IN = 3V, ILOAD = 1mA 2.465 2.5 2.535 V 3.5V < VIN < 20V, 1mA < ILOAD < 50mA l 2.435 2.5 2.565 V 3.5V < VIN < 20V, 1mA < ILOAD < 100mA l 2.415 2.5 2.575 V The l denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) Consult factory for parts specified with wider operating temperature ranges. ABSOLUTE AXI U RATI GSW WW U PACKAGE/ORDER I FOR ATIOUU W

ELECTRICAL CHARACTERISTICS

The l denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS (Note 4) 3.8V < V IN < 20V, 1mA < ILOAD < 50mA l 2.732 2.8 2.868 V 3.8V < VIN < 20V, 1mA < ILOAD < 100mA l 2.706 2.8 2.884 V LT1761-3 V IN = 3.5V, ILOAD = 1mA 2.960 3 3.040 V 4V < VIN < 20V, 1mA < ILOAD < 50mA l 2.930 3 3.070 V 4V < VIN < 20V, 1mA < ILOAD < 100mA l 2.900 3 3.090 V 4.3V < VIN < 20V, 1mA < ILOAD < 50mA l 3.230 3.3 3.370 V 4.3V < VIN < 20V, 1mA < ILOAD < 100mA l 3.190 3.3 3.400 V LT1761-5 V IN = 5.5V, ILOAD = 1mA 4.935 5 5.065 V 6V < VIN < 20V, 1mA < ILOAD < 50mA l 4.900 5 5.100 V 6V < VIN < 20V, 1mA < ILOAD < 100mA l 4.850 5 5.120 V ADJ Pin Voltage LT1761 V IN = 2V, ILOAD = 1mA 1.205 1.220 1.235 V (Note 3, 4) 2.3V < V IN < 20V, 1mA < ILOAD < 50mA l 1.190 1.220 1.250 V 2.3V < VIN < 20V, 1mA < ILOAD < 100mA l 1.170 1.220 1.260 V Line Regulation LT1761-1.5 DVIN = 2V to 20V, ILOAD = 1mA l 11 0 m V LT1761-1.8 DVIN = 2.3V to 20V, ILOAD = 1mA l 11 0 m V LT1761-2 DVIN = 2.5V to 20V, ILOAD = 1mA l 11 0 m V LT1761-2.5 DVIN = 3V to 20V, ILOAD = 1mA l 11 0 m V LT1761-2.8 DVIN = 3.3V to 20V, ILOAD = 1mA l 11 0 m V LT1761-3 DVIN = 3.5V to 20V, ILOAD = 1mA l 11 0 m V LT1761-3.3 DVIN = 3.8V to 20V, ILOAD = 1mA l 11 0 m V LT1761-5 DVIN = 5.5V to 20V, ILOAD = 1mA l 11 0 m V LT1761(Note 3) DVIN = 2V to 20V, ILOAD = 1mA l 11 0 m V Load Regulation LT1761-1.5 V IN = 2.5V, DILOAD = 1mA to 50mA 10 20 mV VIN = 2.5V, DILOAD = 1mA to 50mA l 35 mV VIN = 2.5V, DILOAD = 1mA to 100mA 14 30 mV VIN = 2.5V, DILOAD = 1mA to 100mA l 55 mV LT1761-1.8 V IN = 2.8V, DILOAD = 1mA to 50mA 10 20 mV VIN = 2.8V, DILOAD = 1mA to 50mA l 35 mV VIN = 2.8V, DILOAD = 1mA to 100mA 15 30 mV VIN = 2.8V, DILOAD = 1mA to 100mA l 60 mV LT1761-2 V IN = 3V, DILOAD = 1mA to 50mA 10 20 mV VIN = 3V, DILOAD = 1mA to 50mA l 35 mV VIN = 3V, DILOAD = 1mA to 100mA 15 35 mV VIN = 3V, DILOAD = 1mA to 100mA l 65 mV LT1761-2.5 V IN = 3.5V, DILOAD = 1mA to 50mA 10 20 mV VIN = 3.5V, DILOAD = 1mA to 50mA l 35 mV VIN = 3.5V, DILOAD = 1mA to 100mA 20 40 mV VIN = 3.5V, DILOAD = 1mA to 100mA l 80 mV LT1761-2.8 V IN = 3.8V, DILOAD = 1mA to 50mA 10 20 mV VIN = 3.8V, DILOAD = 1mA to 50mA l 38 mV VIN = 3.8V, DILOAD = 1mA to 100mA 20 40 mV VIN = 3.8V, DILOAD = 1mA to 100mA l 86 mV LT1761-3 V IN = 4V, DILOAD = 1mA to 50mA 10 20 mV VIN = 4V, DILOAD = 1mA to 50mA l 40 mV VIN = 4V, DILOAD = 1mA to 100mA 20 40 mV VIN = 4V, DILOAD = 1mA to 100mA l 90 mV

PARAMETER CONDITIONS MIN TYP MAX UNITS Load Regulation LT1761-3.3 V IN = 4.3V, DILOAD = 1mA to 50mA 10 20 mV VIN = 4.3V, DILOAD = 1mA to 50mA l 40 mV VIN = 4.3V, DILOAD = 1mA to 100mA 20 40 mV VIN = 4.3V, DILOAD = 1mA to 100mA l 100 mV LT1761-5 V IN = 6V, DILOAD = 1mA to 50mA 15 30 mV VIN = 6V, DILOAD = 1mA to 50mA l 60 mV VIN = 6V, DILOAD = 1mA to 100mA 25 65 mV VIN = 6V, DILOAD = 1mA to 100mA l 150 mV LT1761 (Note 3) VIN = 2.3V, DILOAD = 1mA to 50mA 1 6 mV VIN = 2.3V, DILOAD = 1mA to 50mA l 12 mV VIN = 2.3V, DILOAD = 1mA to 100mA 1 12 mV VIN = 2.3V, DILOAD = 1mA to 100mA l 50 mV Dropout Voltage I LOAD = 1mA 0.10 0.15 V VIN = VOUT(NOMINAL) ILOAD = 1mA l 0.19 V (Notes 5, 6, 11) I LOAD = 10mA 0.17 0.22 V ILOAD = 10mA l 0.29 V ILOAD = 50mA 0.24 0.28 V ILOAD = 50mA l 0.38 V ILOAD = 100mA 0.30 0.35 V ILOAD = 100mA l 0.45 V GND Pin Current I LOAD = 0mA l 20 45 mA VIN = VOUT(NOMINAL) ILOAD = 1mA l 55 100 mA (Notes 5, 7) I LOAD = 10mA l 230 400 mA ILOAD = 50mA l 12 m A ILOAD = 100mA l 2.2 4 mA Output Voltage Noise C OUT = 10mF, CBYP = 0.01mF, ILOAD = 100mA, BW = 10Hz to 100kHz 20 mVRMS ADJ Pin Bias Current (Notes 3, 8) 30 100 nA Shutdown Threshold V OUT = Off to On l 0.8 2 V VOUT = On to Off l 0.25 0.65 V SHDN Pin Current V SHDN = 0V l 0 0.5 mA (Note 9) V SHDN = 20V l 13 mA Quiescent Current in Shutdown V IN = 6V, VSHDN = 0V 0.01 0.1 mA Ripple Rejection (Note 3) V IN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, 55 65 dB ILOAD = 50mA Current Limit V IN = 7V, VOUT = 0V 200 mA VIN = VOUT(NOMINAL) + 1V, DVOUT = –5% l 110 mA Input Reverse Leakage Current V IN = –20V, V OUT = 0V l 1m A Reverse Output Current LT1761-1.5 V OUT = 1.5V, VIN < 1.5V 10 20 mA (Note 10) LT1761-1.8 V OUT = 1.8V, VIN < 1.8V 10 20 mA LT1761-2 V OUT = 2V, VIN < 2V 10 20 mA LT1761-2.5 V OUT = 2.5V, VIN < 2.5V 10 20 mA LT1761-2.8 V OUT = 2.8V, VIN < 2.8V 10 20 mA LT1761-3 V OUT = 3V, VIN < 3V 10 20 mA LT1761-3.3 V OUT = 3.3V, VIN < 3.3V 10 20 mA LT1761-5 V OUT = 5V, VIN < 5V 10 20 mA LT1761 (Note 3) VOUT = 1.22V, VIN < 1.22V 5 10 mA The l denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) TA = 25°C. Performance at –40 °C and 125°C is assured by design, characterization and correlation with statistical process controls. Note 3: The LT1761 (adjustable versions) are tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1761 regulators are tested and specified under pulse load conditions such that TJ » TA. The LT1761 is 100% production tested at

OUTPUT CURRENT (mA) 500 450 400 350 300 250 200 150 100 DROPOUT VOLTAGE (mV)

1761 G01

0 1 02 03 0 40 50 60 70 80 90 100 TJ ≤ 125°C TJ ≤ 25°C = TEST POINTS TEMPERATURE (°C) –50 QUIESCENT CURRENT (µA) 100

1761 G03

–25 25 75 125 VIN = 6V RL = ∞ (250k FOR LT1761-BYP, -SD) IL = 0 (5µA FOR LT1761-BYP, -SD) VSHDN = VIN VSHDN = 0V TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G06

1.84 1.83 1.82 1.81 1.80 1.79 1.78 1.77 1.76 –25 25 75 125 IL = 1mA Guaranteed Dropout Voltage Quiescent Current LT1761-1.8 Output Voltage Dropout Voltage TEMPERATURE (°C) –50 DROPOUT VOLTAGE (mV) 0 50 75 1761 G01.1 –25 25 100 125 IL = 100mA IL = 50mA IL = 10mA IL = 1mA 500 450 400 350 300 250 200 150 100 OUTPUT CURRENT (mA) 500 450 400 350 300 250 200 150 100 DROPOUT VOLTAGE (mV)

1761 G00

0 1 02 03 0 40 50 60 70 80 90 100 TJ = 125°C TJ = 25°C Typical Dropout Voltage Note 4: Operating conditions are limited by maximum junction temperature. The regulated output voltage specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current, the input voltage range must be limited. Note 5: To satisfy requirements for minimum input voltage, the LT1761 (adjustable version) is tested and specified for these conditions with an external resistor divider (two 250k resistors) for an output voltage of 2.44V. The external resistor divider will add a 5mA DC load on the output. Note 6: Dropout voltage is the minimum input to output voltage differential needed to maintain regulation at a specified output current. In dropout, the output voltage will be equal to: V IN – VDROPOUT. Note 7: GND pin current is tested with VIN = VOUT(NOMINAL) or VIN = 2.3V (whichever is greater) and a current source load. This means the device is tested while operating in its dropout region or at the minimum input voltage specification. This is the worst-case GND pin current. The GND pin current will decrease slightly at higher input voltages. Note 8: ADJ pin bias current flows into the ADJ pin. Note 9: SHDN pin current flows into the SHDN pin. Note 10: Reverse output current is tested with the IN pin grounded and the OUT pin forced to the rated output voltage. This current flows into the OUT pin and out the GND pin. Note 11: For the LT1761, LT1761-1.5, LT1761-1.8 and LT1761-2 dropout voltage will be limited by the minimum input voltage specification under some output voltage/load conditions. See the curve of Minimum Input Voltage in the Typical Performance Characteristics. TYPICAL PERFOR A CE CHARACTERISTICS UW TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G51

1.528 1.521 1.514 1.507 1.500 1.493 1.486 1.479 1.472 –25 25 75 125 IL = 1mA LT1761-1.5 Output Voltage

INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G18

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V LT1761-1.8 Quiescent Current LT1761-BYP, LT1761-SD ADJ Pin Voltage TEMPERATURE (°C) –50 ADJ PIN VOLTAGE (V) 100

1761 G10

1.240 1.235 1.230 1.225 1.220 1.215 1.210 1.205 1.200 –25 25 75 125 IL = 1mA LT1761-5 Output Voltage TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G12

5.08 5.06 5.04 5.02 5.00 4.98 4.96 4.94 4.92 –25 25 75 125 IL = 1mA TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G08

2.54 2.53 2.52 2.51 2.50 1.49 1.48 1.47 1.46 –25 25 75 125 IL = 1mA LT1761-2.5 Output Voltage TYPICAL PERFOR A CE CHARACTERISTICS UW TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G07

2.04 2.03 2.02 2.01 2.00 1.99 1.98 1.97 1.96 –25 25 75 125 IL = 1mA LT1761-2 Output Voltage LT1761-2.8 Output Voltage TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G09

3.060 3.045 3.030 3.015 3.000 2.985 2.970 2.955 2.940 –25 25 75 125 IL = 1mA LT1761-3 Output Voltage LT1761-3.3 Output Voltage TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G11

3.360 3.345 3.330 3.315 3.300 3.285 3.270 3.255 3.240 –25 25 75 125 IL = 1mA TEMPERATURE (°C) –50 OUTPUT VOLTAGE (V) 100

1761 G52

2.84 2.83 2.82 2.81 2.80 2.79 2.78 2.77 2.76 –25 25 75 125 IL = 1mA LT1761-1.5 Quiescent Current INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G53

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V

INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G02

TJ = 25°C *FOR VOUT = 1.8V RL = 18Ω IL = 100mA* RL = 36Ω IL = 50mA* RL = 180Ω IL = 10mA* RL = 1.8k IL = 1mA* LT1761-1.8 GND Pin Current LT1761-3.3 Quiescent Current LT1761-5 Quiescent Current INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G15

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G16

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V INPUT VOLTAGE (V) 02 6 1 0 1 4 1 8 QUIESCENT CURRENT (µA) 4 8 12 16

1761 G17

TJ = 25°C RL = 250k IL = 5µA VSHDN = VIN VSHDN = 0V LT1761-BYP, LT1761-SD Quiescent Current TYPICAL PERFOR A CE CHARACTERISTICS UW LT1761-3 Quiescent Current INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G14

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G19

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V LT1761-2 Quiescent Current LT1761-2.5 Quiescent Current INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G13

VSHDN = VIN TJ = 25°C RL = ∞ VSHDN = 0V LT1761-2.8 Quiescent Current INPUT VOLTAGE (V) QUIESCENT CURRENT (µA) 200 175 150 125 100

1761 G54

TJ = 25°C RL = ∞ VSHDN = 0V VSHDN = VIN LT1761-1.5 GND Pin Current INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G55

TJ = 25°C *FOR VOUT = 1.5V RL = 15Ω IL = 100mA* RL = 30Ω IL = 50mA* RL = 150Ω IL = 10mA* RL = 1.5k IL = 1mA*

INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G24

TJ = 25°C *FOR VOUT = 1.22V RL = 12.2Ω IL = 100mA* RL = 24.4Ω IL = 50mA* RL = 122Ω IL = 10mA* RL = 1.22k IL = 1mA* OUTPUT CURRENT (mA) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G25

0 1 02 03 0 40 50 60 70 80 90 100 VIN = VOUT(NOMINAL) + 1V LT1761-BYP, LT1761-SD GND Pin Current GND Pin Current vs ILOAD TEMPERATURE (°C) –50 SHDN PIN THRESHOLD (V) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 50 75

1761 G26

–25 25 100 125 IL = 1mA SHDN Pin Threshold (On-to-Off) TYPICAL PERFOR A CE CHARACTERISTICS UW INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G04

TJ = 25°C *FOR VOUT = 2V RL = 20Ω IL = 100mA* RL = 40Ω IL = 50mA* RL = 200Ω IL = 10mA* RL = 2k IL = 1mA* LT1761-2 GND Pin Current LT1761-2.5 GND Pin Current INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G20

TJ = 25°C *FOR VOUT = 2.5V RL = 25Ω IL = 100mA RL = 50Ω IL = 50mA* RL = 250Ω IL = 10mA* RL = 2.5k IL = 1mA* LT1761-3 GND Pin Current INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G21

TJ = 25°C *FOR VOUT = 3V RL = 30Ω IL = 100mA* RL = 60Ω IL = 50mA* RL = 300Ω IL = 10mA* RL = 3k IL = 1mA* INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G22

TJ = 25°C *FOR VOUT = 3.3V RL = 33Ω IL = 100mA* RL = 66Ω IL = 50mA* RL = 330Ω IL = 10mA* RL = 3.3k IL = 1mA* LT1761-3.3 GND Pin Current INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G23

TJ = 25°C *FOR VOUT = 5V RL = 50Ω IL = 100mA RL = 100Ω IL = 50mA* RL = 500Ω IL = 10mA* RL = 5k IL = 1mA* LT1761-5 GND Pin Current LT1761-2.8 GND Pin Current INPUT VOLTAGE (V) 2.50 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 GND PIN CURRENT (mA)

1761 G56

TJ = 25°C *FOR VOUT = 2.8V RL = 28Ω IL = 100mA RL = 56Ω IL = 50mA* RL = 280Ω IL = 10mA* RL = 2.8k IL = 1mA*

Reverse Output Current Reverse Output Current OUTPUT VOLTAGE (V) 100 REVERSE OUTPUT CURRENT (µA)

1761 G33

TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN V OUT = VADJ (LT1761-BYP, -SD) LT1761-BYP LT1761-SD LT1761-2 LT1761-3.3 LT1761-5 LT1761-1.8 LT1761-1.5 LT1761-2.5 LT1761-2.8 LT1761-3 TEMPERATURE (°C) –50 REVERSE OUTPUT CURRENT (µA) 25.0 22.5 20.0 17.5 15.0 12.5 10.0 7.5 5.0 2.5 0 50 75

1761 G34

–25 25 100 125 VIN = 0V VOUT = 1.22V (LT1761-BYP, -SD) VOUT = 1.5V (LT1761-1.5) VOUT = 1.8V (LT1761-1.8) VOUT = 2V (LT1761-2) VOUT = 2.5V (LT1761-2.5) VOUT = 2.8V (LT1761-2.8) VOUT = 3V (LT1761-3) VOUT = 3.3V (LT1761-3.3) VOUT = 5V (LT1761-5) LT1761-BYP,-SD FREQUENCY (Hz) RIPPLE REJECTION (dB) 10 1k 10k 1M

1761 G35

IL = 100mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE CBYP = 0 COUT = 1µF COUT = 10µF LT1761-BYP LT1761-5 Input Ripple Rejection TYPICAL PERFOR A CE CHARACTERISTICS UW SHDN Pin Input Current ADJ Pin Bias Current Current Limit TEMPERATURE (°C) –50 SHDN PIN INPUT CURRENT (µA) 0 50 75

1761 G29

–25 25 100 125 VSHDN = 20V 1.4 1.2 1.0 0.8 0.6 0.4 0.2 TEMPERATURE (°C) –50 ADJ PIN BIAS CURRENT (nA) 100 0 50 75

1761 G30

–25 25 100 125 INPUT VOLTAGE (V) SHORT-CIRCUIT CURRENT (mA) 2 4 5

1761 G31

VOUT = 0V TJ = 25°C Current Limit TEMPERATURE (°C) –50 CURRENT LIMIT (mA) 0 50 75

1761 G32

–25 25 100 125 350 300 250 200 150 100 VIN = 7V VOUT = 0V SHDN PIN VOLTAGE (V) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 SHDN PIN INPUT CURRENT (µA)

1761 G28

TEMPERATURE (°C) –50 SHDN PIN THRESHOLD (V) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 50 75

1761 G27

–25 25 100 125 IL = 100mA IL = 1mA SHDN Pin Threshold (Off-to-On)

Output Noise Spectral Density FREQUENCY (Hz) 10 1k 10k 100k

1761 G41

0.1 0.01 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) COUT = 10µF CBYP = 0 IL = 100mA LT1761-BYP, -SD LT1761-5 LT1761-3.3 LT1761-2.8,-3 LT1761-2.5 LT1761-1.8 LT1761-2 LT1761-1.5 FREQUENCY (Hz) 10 1k 10k 100k

1761 G42

0.1 0.01 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) LT1761-BYP LT1761-5 CBYP = 1000pF CBYP = 0.01µF CBYP = 100pF COUT = 10µF IL = 100mA CBYP (pF) OUTPUT NOISE (µVRMS) 140 120 100 100 1k 10k

1761 G43

COUT = 10µF IL = 100mA f = 10Hz TO 100kHz LT1761-5 LT1761-3.3 LT1761-3 LT1761-2.8 LT1761-2.5 LT1761-1.5 LT1761-1.8, -2 LT1761-BYP Output Noise Spectral Density RMS Output Noise vs Bypass Capacitor TYPICAL PERFOR A CE CHARACTERISTICS UW FREQUENCY (Hz) RIPPLE REJECTION (dB) 10 1k 10k 1M

1761 G36

IL = 100mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE COUT = 10µF CBYP = 0.01µF CBYP = 100pF CBYP = 1000pF TEMPERATURE (°C) –50 RIPPLE REJECTION (dB) 100

1761 G37

–25 25 75 125 VIN = VOUT (NOMINAL) + 1V + 0.5VP-P RIPPLE AT f = 120Hz I L = 50mA LT1761-5 Input Ripple Rejection Input Ripple Rejection LT1761-BYP, LT1761-SD Minimum Input Voltage Load Regulation DIL = 1mA to 50mA TEMPERATURE (°C) –50 MINIMUM INPUT VOLTAGE (V) 2.5 2.0 1.5 1.0 0.5 0 50 75

1761 G38

–25 25 100 125 IL = 100mA IL = 50mA TEMPERATURE (°C) –50 LOAD REGULATION (mV) 100

1761 G39

–10 –15 –20 –25 –3 0 –35 –40 –25 25 75 125 LT1761-BYP, -SD LT1761-1.8 LT1761-1.5 LT1761-2 LT1761-2.5 LT1761-2.8 LT1761-3 LT1761-3.3 LT1761-5 TEMPERATURE (°C) –50 LOAD REGULATION (mV) 100

1761 G40

–10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –25 25 75 125 LT1761-3 LT1761-2 LT1761-2.5 LT1761-2.8 LT1761-5 LT1761-3.3 LT1761-BYP, -SD LT1761-1.8 LT1761-1.5 Load Regulation DIL = 1mA to 100mA

LT1761-5 Transient Response CBYP = 0 TIME (µs) 0.2 0.1 –0.1 –0.2 OUTPUT VOLTAGE DEVIATION (V) 100 LOAD CURRENT (mA)

1761 G49

VIN = 6V CIN = 10µF COUT = 10µF TIME (µs) 0.04 0.02 –0.02 –0.04 OUTPUT VOLTAGE DEVIATION (V) 100 LOAD CURRENT (mA)

1761 G50

04 0 6 0 1 0 020 80 120 140 180160 200 VIN = 6V CIN = 10µF COUT = 10µF LT1761-5 Transient Response CBYP = 0.01mF TYPICAL PERFOR A CE CHARACTERISTICS UW LT1761-5 10Hz to 100kHz Output Noise C BYP = 0 VOUT 100mV/DIV LT1761-5 10Hz to 100kHz Output Noise CBYP = 100pF 1ms/DIV COUT = 10mF IL = 100mA 1761 G46 VOUT 100mV/DIV 1ms/DIV COUT = 10mF IL = 100mA 1761 G45 LOAD CURRENT (mA) 0.01 OUTPUT NOISE (µVRMS) 160 140 120 100 0.1 1

1761 G44

COUT = 10µF LT1761-5 LT1761-5 LT1761-BYP LT1761-BYP CBYP = 0 CBYP = 0.01µF RMS Output Noise vs Load Current (10Hz to 11kHz) LT1761-5 10Hz to 100kHz Output Noise CBYP = 1000pF VOUT 100mV/DIV LT1761-5 10Hz to 100kHz Output Noise C BYP = 0.01mF 1ms/DIV COUT = 10mF IL = 100mA 1761 G48 VOUT 100mV/DIV 1ms/DIV COUT = 10mF IL = 100mA 1761 G47

function if the SHDN pin is not connected. For the LT1761-BYP, the SHDN pin is internally connected to VIN. BYP (Pins 3/4, Fixed/-BYP Devices): Bypass. The BYP pin is used to bypass the reference of the LT1761 regula- tors to achieve low noise performance from the regulator. The BYP pin is clamped internally to –0.6V (one V BE) from ground. A small capacitor from the output to this pin will bypass the reference to lower the output voltage noise. A maximum value of 0.01mF can be used for reducing output voltage noise to a typical 20mV RMS over a 10Hz to 100kHz bandwidth. If not used, this pin must be left unconnected. ADJ (Pin 4, Adjustable Devices Only): Adjust Pin. For the adjustable LT1761, this is the input to the error amplifier. This pin is internally clamped to –7V. It has a bias current of 30nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Char- acteristics section). The ADJ pin voltage is 1.22V referenced to ground and the output voltage range is 1.22V to 20V. OUT (Pin 5): Output. The output supplies power to the load. A minimum output capacitor of 1 mF is required to prevent oscillations. Larger output capacitors will be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. IN (Pin 1): Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if the device is more than six inches away from the main input filter capacitor. In general, the output impedance of a battery rises with frequency, so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 1 mF to 10 mF is sufficient. The LT1761 regulators are designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reverse input, which can happen if a battery is plugged in backwards, the device will act as if there is a diode in series with its input. There will be no reverse current flow into the regulator and no reverse voltage will appear at the load. The device will protect both itself and the load. GND (Pin 2): Ground. SHDN (Pin 3, Fixed/-SD Devices): Shutdown. The SHDN pin is used to put the LT1761 regulators into a low power shutdown state. The output will be off when the SHDN pin is pulled low. The SHDN pin can be driven either by 5V logic or open-collector logic with a pull-up resistor. The pull-up resistor is required to supply the pull-up current of the open-collector gate, normally several microamperes, and the SHDN pin current, typically 1 mA. If unused, the SHDN pin must be connected to V IN. The device will not UUUPI FU CTIO S APPLICATIO S I FOR ATIOWU UU The LT1761 series are 100mA low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 100mA at a dropout voltage of 300mV. Output voltage noise can be lowered to 20mV RMS over a 10Hz to 100kHz bandwidth with the addition of a 0.01mF reference bypass capacitor. Additionally, the refer- ence bypass capacitor will improve transient response of the regulator, lowering the settling time for transient load conditions. The low operating quiescent current (20 mA) drops to less than 1mA in shutdown. In addition to the low quiescent current, the LT1761 regulators incorporate sev- eral protection features which make them ideal for use in battery-powered systems. The devices are protected against both reverse input and reverse output voltages. In battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the LT1761-X acts like it has a diode in series with its output and prevents reverse current flow. Additionally, in dual supply applications where the regulator load is returned to a negative supply, the output can be pulled below ground by as much as 20V and still allow the device to start and operate. Adjustable Operation The adjustable version of the LT1761 has an output voltage range of 1.22V to 20V. The output voltage is set by the ratio of two external resistors as shown in Figure 1. The device servos the output to maintain the ADJ pin voltage at 1.22V referenced to ground. The current in R1 is then

Figure 1. The value of R1 should be no greater than 250k pin tied to the OUT pin for an output voltage of 1.22V.

1761 F01

Figure 1. Adjustable Operation has the added benefit of improving transient response. bypass capacitor and 10mF output capacitor. bypass capacitance used, while the maximum ESR is 3W . Figure 2. Stability

1761 F02

is available in higher values. Figure 4. Ceramic Capacitor Temperature Characteristics Figure 3. Ceramic Capacitor DC Bias Characteristics

1761 F04

1210 CASE SIZE, 10µF

1761 F03

masquerade as increased output voltage noise. Figure 5. Noise Resulting from Tapping on a Ceramic Capacitor

Output current multiplied by the input/output voltage
GND pin current multiplied by the input voltage:

sum of the two components listed above. all sources of thermal resistance from junction to ambient.

Table 1. Measured Thermal Resistance *Device is mounted on topside. and reverse voltages from output to input. tion, the junction temperature should not exceed 125°C. which can be plugged in backward. stop the output from sourcing the short-circuit current. diode when pulled above ground. from the 1.22V reference when the output is forced to 20V.

Dimensions in inched (millimeters) unless otherwise noted.

DIMENSIONS ARE IN MILLIMETERS
DIMENSIONS ARE INCLUSIVE OF PLATING
DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
MOLD FLASH SHALL NOT EXCEED 0.254mm
PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)

pin yields a minimum top resistor value of 2.6k. Figure 6. Reverse Output Current

1761 F06

current when the output is pulled above the input. Burst Mode is a trademark of Linear Technology Corporation.

Product Information

LT1761 specifications and overview.

Summary

Low Dropout Negative Micropower Regulator in ThinSOT

Description

Low Dropout Negative Micropower Regulator in ThinSOT

Source title LT1761 Datasheet(PDF) - Linear Technology

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